DE1589438A1 - Laser structure - Google Patents

Description

Priority? USAj March 31, 1966 j """""" US Serial No. 539 041.

The invention relates to arrangements, structures and the like. Like. For laser light generation and laser light amplification, in which thin elongated laser rods or fibers are used and flash tube devices formed from glass are assigned to them. You invention deals to produce such structures more economically and to be able to operate it more effectively than was previously the case with comparable earlier laser structures.

More specifically, the invention relates to laser structures and the like, in each of which a thin elongated laser et ab, or a vaeer, and a flash tube device provided and these in integral uniform construction

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Bayeriidi «Veieinibank Munich 820963

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tion are trained. The invention is concerned with this Bit improvements that make these devices or structures not only more robust, “more durable, easier and more Make more economical to manufacture than before, but also have the success that the device or Arrangement according to the invention according to shape, geometric Proportions, configurations and layouts allow a closer or denser optical coupling of their component parts as well as a faster and more efficient one Conductivity and heat dissipation to the outside, as it can be carried out so far, you can use laser structures in accordance with of the invention can be operated more effectively continuously or intermittently at a relatively high repetition rate than before, and they give a greater laser emission result and a higher gain, ie a higher gain per unit length relative to the input energy than before.

Furthermore, in such integrated structures, the alignment of the parts with one another is permanently built into the device Materials of rod and support and adapted indices tone rod and support a control over the choice of Vibration form and the propagation received · If also the GIa * of the laser rod and da · 01a «« of a support

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(This on lay glass / also forms the side wall sections of the flash tube section of the arrangement and can thus be used in appropriately, catfish are referred to as the "main body part") correctly in terms of their absorption characteristics and other associated characteristics are selected "as will be described in more detail below an energy storage unit and / or an independent or built-in one Q-Schaltanordming received.

There are already such laser units known that relatively thin elongated laser rods or fibers made of laser glass and use them side by side nlt one Arrange electronic flash tube or the like so that the Pumping from the side laer takes place. These ropes were over the greater part of its length with highly reflective Aluminum foil o. The like. Surrounded by as large a proportion of the optical pump energy as possible from the flash tube into the laser rod or the Fiber meanwhile, bxw. direct their operation can. Furthermore, «an has already let water or air circulate between these laser parts and around them in order to try to determine the optical efficiency of these Improve lasers.

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However, with the earlier laser units and Constructions have proven that on the one hand, they the efficiency of the operation and the achievable output power were relatively limited and also in terms of the speed with which it is operated in pulse mode by the associated flash tube device could be, because otherwise excessive amounts of heat are generated during the Laserbe operations that lead to destruction.

It has now been found that the teaching of the invention described below Bene a laser operation with higher efficiency than before and a significantly improved repetition rate in pulse mode, or even with continuous Operation where a laser structure can be obtained in which a thin elongated glass laser rod, or fiber, and an associated flash tube device are provided · You improved laser structure is made practical by achieves an arrangement that one might call an illegitimate one, so to speak Integral, independent and self-contained structural arrangement can denote} in this arrangement a thin elongated rod, or a fiber, made of laser glass of known type and with the desired refractive index and other optical and physical properties and incorporated within a main body part,

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formed of a selected type of transparent GIa * and closely associated index of refraction in such a manner that it is in intimate contact with substantially all of the rare wall portions of the rod or the like; At the same time, an elongated bore is provided within the glass of the main body part, which is located side by side essentially parallel in close proximity to the laser rod, or the fiber, so that it forms a light chamber for the laser light source of the laser unit.In addition, it is integrally thin and a long assembly of flash tube and laser rod provided on its outer surface with a highly light-reflecting first metallic layer and a second, thicker, thermally conductive metallic layer of high conductivity. The cross-sectional area of the main body portion is kept as small as is conveniently possible in accordance with good engineering design so that not only is an optically tightly coupled arrangement obtained, but also an understanding of healing of the light from the flash tube before the light hits the laser lens enter · In this way one obtains a · good radial thermal conductivity of the Blitslichtröhrenkamaer only by glass and a · tchntlle heat dissipation ron the structure * self dl · shape of the cross section ·· dta 18rper · can be controlled so that a better · Seflektion d " s Flash tube light takes place in the direction of the laser rod. Since the laser

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rod, or the fiber, and the material of the main body Both are glass »the unit can be made relatively long and thin for better operating efficiency. It Is also possible the material of the main body mechanically by the metallic first and second layers or coverings.

The invention therefore relates to a unitary, integral, thin, elongated laser system having the following properties: It has a main body part which is made for optical energy of a predetermined pump wavelength transparent and having a known refractive index Glass is made; An elongated rod, or fiber, made of laser glass bits of closely matched refractive index is embedded in the main body portion and extends substantially from one end to the other in the main body portion a bore is formed in the main body part and extends over the greater part of the length of the main body part in close proximity and essentially parallel to the rod or the shaft. the bore is closed at both ends and contains an ionizable gas} a pair of electrodes is carried by the main body part and extends into the bore near the two ends so that a flash tube chamber is formed therein is} on the outer rare wall absorbencies of the main body

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parts is a layer of highly reflective Ketallmaterial arranged and is located with this in intimate contact «u» optical pump energy that is in the Hole is produced., Sighting for the lasers tab, or The fibers reflect s while at the same time quickly dissipating heat generated within the structure to the outside; this laser system provides a close optical coupling and an effective arrangement for cooling with radial derivation «

The invention also provides a thin, elongated, unitary, integral laser system with an elliptical or approximately elliptical configuration of the outer cross-section the main body part; this makes it more effective Concentration of the pumping light rays generated on the laser rod or on the fiber, while keeping a minimum of internal Re flection and effective dissipation or dispersion the heat generated during laser operation is achieved.

According to the invention is also such a thin elongated closely coupled laser structure provided with reflective surface coatings on the both band walls of the laser rod or its paser section are provided; this creates an optical resonance cavity between the covered end panels

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trained, and a laser operation, can with a substantially, Receive reduced input energy input and maintained continuously, or at least at a relatively rapid pulse repetition rate.

Haoh of the invention can also be applied to the outer reflective first layer on the thin elongated main body part of the laser structure or system in intimate Contact with the first layer is relatively thick metallic layer of relatively high thermal conductivity so it should be provided that an effective means of dissipating the heat generated during operation is obtained generated in the laser system *

The invention is schemati sher in the following by hand Drawings of several exemplary embodiments explained in more detail.

Pig. 1 shows a length cross-section of a laser unit or a structure according to the invention;

FIG. 2 is an enlarged perspective and partially broken view of a portion of the structure of FIG. 1 including a cross-section substantially along section line 2-2 of FIG. 1 $

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Pig. 3 is an enlarged cross-section of a modified embodiment of the invention; and

Fig. 4- is a broken away cross-section of a further modification of the invention.

1 shows a laser unit or a laser construction 10 which has very little cash, tree requirements and weight and la essentially has a thin elongated main body part 12 made of glass with such optical and physical properties that it is compatible with the laser glass still used and for the optical energy at least certain of the preselected pump wavelengths required to pump from the side is transparent and to be able to transfer energy to the laser glass used.

Within this file 12 extends through the whole Length of a rod, or a fiber, 14 »made of laser glass, known Kind, whereby the laser glass is a barium crown glass with the addition of trivalent neodia, a laser glass with the addition of erbium * Ytterbium neodymium, a laser glass with the addition of Ytterblum-KTeodym or the like. with a predetermined refractive index value can be used. It should be noted that the value of the refractive index of the glass dta main body parts 12 carefully la relation to the laser that is used at the same time.

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glass must be determined and controlled so that an interface 13 between the: laser glass and the main body part has a refractive index difference with the desired value «

In some cases, the refractive index of the laser glass will be significantly greater than the refractive index desired for the main body part, the main body part then serving as a support material for the laser rod. This is the case when the choice of the operating vibration and the propagation conditions are not essential factors. For other purposes, however, it can sometimes be preferable if the support glass has only a slightly smaller refractive index value than the laser glass, in order to obtain a low-order vibration propagation state within the laser range. In such cases, only low-order vibration states are passed on ßindexdi fieren * between core and support of only one to two parts per thousand, and the beam broadening of the laser or the fiber can be limited to no more than 3 ° or a similar value. As will also be described later, at other times and for other purposes a slightly higher refractive index value of the overlay material than the laser glass may be desired and provided «

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Within the main body part * 12 there is also provided, extending in the longitudinal direction, a hollow-cylinder-like bore 16, which is that of the laser set or the auger 14 is closely adjacent and see essentially side mn side ait this »bsw. this parallel he stretches. The Bonrang 16 is bits of a highly polished, cylindrically shaped inner surface 16 'at both ends closed by suitable gowns so that it forms a gas-tight K-asaer 13, within which an ionizable Sas, such as xenon, argon, helium o. The like, or a uasBischung, is included "

It ends of the bore 16 to geseigten Aueführungsform are terminated by electrodes 20 and 22 * · ^η hineinrsrlaufen the bore and ο is rigidly mitt ice ^ a Epoxyieeentee 24th Before the electrodes are inserted, the two end surfaces 12a and 12b of the main body part and the laser rod, or the fiber, are polished, and a cover or coating 25 and 27, or a pair thereof, is applied to these polished end surfaces arranged according to Vunsch.

In one construction, these can be used in a known manner be made of highly reflective metal material, or of dichroic a bxw. two-color

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ge »material that contributes to the optical energy ■ certain selected laser emission wavelength or is highly reflective of such wavelengths " BAe is the case when an optical fieeonan cavity for laser lights * eugungeavecke or the like * is desired is · In such cases, of course, at least one of the layers or covers is designed so that a small percentage of permeability is possible, so that optical energy of the selected emission wavelength to the outside through, the coating or cover can pass through, as indicated by the arrow 29 «

In slightly modified laser arrangements, such as the bistable laser construction according to the German Easter application A 4-9 483 of June 15, 1965, generally a laser apparatus with a soluble absorber according to the German application A 53 972 October 31 1966 and also in the case of the glaze construction "it Q-circuit ge" tS of the USA, patent from Roester Ir " 3 281 712, which was granted on October 25, 1966, one of the highly reflective can escape or both can be aligned with a distance and correctly oriented opposite the »Bfcd * or the ends of the laser rod or the auger. It is possible to use suitable filters or mechanical means to “wipe” a “sol @ nen” reflector arranged at a distance and the liöKÄciibärfce / s. Ends of the laser point

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If the lay structure ron fig * 1 f @ b? children should be used, days 25 and 2? instead of being formed in the known way by multiple layers of low reflection, so that, for example, a light signal is effectively scanned into it by a laser rod or the fiber; will »tind the reratlrte lexerlightsignaa easily get through the other end to the outside kana. To the "same SSeIt of erreiohbaren Yeretirkungaeradee can take the * sen end faces what a Hiniau" internal LichtrefleSctionen entetehen five such light reflections would Gonet »u a result,

In one of the electrodes 20, according to FIG. 1, a lingeduxchgeag 26 is formed, which directly connects to the inner space 18 of the bore 16 with a long opening 26a la connection. In this catfish is the kaan lammer 18 anaohließend to the Einsemtntierem the electrode or another entspreokenden Torgaag warning attaching electrodes to their Plats dlesea passage erakuieren, while doing a case of "

Migang central hollow-side electrical charge; ing the charging of the seat Asstsmd asfeordinated electrodes 20 and 22 is done · AneeaiieAend is lemon or another QmB or »eartrt this oasis in the chamber 18!» raneÄseiÄießead the DurohlaB 26 is used afterwards »You can sometimes see their cross winds

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thick; and, if necessary, a * Spoxyaemaat seals _t like «β is indicated at 28 and 28a« These electrodes can be made of copper tube, which has ine gate thermal conductivity, and can be placed in your longer booths with tungsten caps 53a and 53fc if necessary * ~ Be late, so that it is better to resist the Hi ta β and wasrem operational conditions, while the continui is running or with a honed recovery period, the device takes place. A sack of the legs can frigger By taking the light tube over one of the electrodes

In? Ig. 2 it can be seen that the dännen iangge * stretched Hauptkörptrteile a first Besektohtnmg or cover made of highly reflective Hetallmaterial ₉ Torsugeweise silver is on the äuSaren, aoongra * dig polished Seitenvandabsennltten 1Sc 12 30 arranged _t, because silver has the Manea infrared part of the spectrum better Llohtreflektlonsflnickeit than other metals, such as aluminum, and on the outer surface of the layer or cover 30 is a somewhat heavier metallic, wide cover or base 52 made of highly insulating material, copper or the like.

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In Fig. 2, asm recognizes a cross-section of a rusted form of a thin elongated unitary integral structure in which a fairly close optical coupling "between the bliteliohtrshrenfcaiBmer 13 and the laser" tab or oat fiber "which are closely adjacent to one another; are, is achieved "an operable size for a laser unit of this type for the continuous or fast pulse mode with Iiaserfaeer and high Betriebswirkungagrad with good radial heat transfer cm o may be about at lengths of 25 _t. 4 · the like are, and the diameter of Laeerstabes b * w «His' fiber section a can be about a willimeter · The hole for the slit light tube can be about 2 millimeters in diameter«

If you look at Yier-Siraau laser glass with such a construction used with trivalent tfeodymium * is without liquid cooling Laser operation possible at room temperature with a laser output at a wavelength of 1.06 microns signal has 10 watts in a 30 flillijoul "pulse" if, a pulse train tone 10 pulses per second for a longer operating time is provided · Above the Threshold values are obtained in this Yl8r-2fiYe * u ~ 8y "t" i high efficiency with low fleece at the end · and sequentially, relatively high strength «da« in long

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ger laser rod or a corresponding Jtaser the hotwen-. The ability of a smaller gain per unit of length and a correspondingly smaller inversion per unit volume results and, in addition, such long rods are also lighter can be cooled quickly “However, good results can also be achieved with other measurement values.

With such an arrangement, the laser glass is in intimate contact with the glass that forms the main body part, and its volume is kept as small as is conveniently possible a combination of GIaS ₁ then air "and then again glass as before)" is the consequence that "light hits the laser glass faster and is absorbed. The situation is different than usual" where the light is around di for a predetermined period of time The inside of the structure can crackle and unwanted fieXlection losses on the silver every time it hits the surrounding yeast reflector and is also exposed to high thermal levels.

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The metallic Beeciiiolitamgen on the Auflenaei be des Main body parts do not wear nua? to dissipate the heat generated during operation of the device at » but give this relatively thin long and otherwise fragile-appearing structure in addition to mechanical strength. The silver of the first leaking line becomes heavy on its outside The copper license located thereon is protected. If, furthermore, the main body part 12 is made of glass with ultraviolet absorption, the inner surface of the sirberbeechlchtuag is thereby also filled.

According to Fig. 3, the main body part 12 'in its design of the outer cross-section it can be controlled so that an ellipse or aodiflsi «rt« ellipse is formed at that of the I> a * first or dl · fiber 14 'is arranged near the one focal point of the ellipse and the flash light chamber 18 is arranged near the other focal point of the ellipse. In this way »an gets a spatial arrangement in which one still more effective Eapfang dt * light is guaranteed «because * of the various parts dtr consisting of silver first coating the outer surface of the main body part is reflected. She "far" is copper-coated 32 'shown. In addition, * vit is shown KebrisM τοη radiel T «rlauf * Äd # n Eühlrippta 53 * us Kttall good V & wteititflidgksit dsuxah V» ioh- odtr Hart-

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Solder ο, the like. Firmly on the outer surface of the layer 32 ' The environment can be connected from sennit ts ~ be done wisely so that a suitable transverse course is given along the structure, or the lips can be arranged rectilinearly in such a way be that they run in the longitudinal direction of the structure ent Hips of the latter type are shown at 40 · Accordingly this creates additional outer surface areas © to dissipate heat from the laser structure If sometimes an even greater cooling effect for the Structure or aggregate is desired, too possible to use an outer two-part cover & jacket " as indicated at 42, provide * the over the larger rope extends the length of the structure and through which a coolant, such as air or water, is pumped can be·

The laser rod or the fiber of the unit according to the invention can be more special for some purposes with a glass The type and controlled bead must be covered in such a way that this assignment between the laser material and the "glass de" surrounds it Main body parts is arranged. Such an arrangement is shown in FIG from special gas is denoted by 44 · How to eitht, i * t the glass of this feiles 44 in iatises contact with both the glass of the main body 12 · and d «& X. & ß®rstab 14 * ·

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The laser glass of the feiles 14 "canoe for example Barium crown glass can be made with the addition of trivalent heodymium, which has already been mentioned, and can gut have a relatively high predetermined index of refraction The covering glass 44 can also be saturable glass with a protective additive with only a very slightly higher refractive index and may have an addition of the type described in the German Snitzer application A 49 484 of $ 1. June 1965 is described. In this application are the following divalent addition ions mentioned in the mother glassJ - Nickel, cobalt, copper and iron -j are also those following trivalent addition ions in the glass: - vanadium, samarium, dysprosium, praseodymium, europium., terbium, holmium, Gadolinium and! Thulium mentioned, and also the trivalent ones Addition ions of uranium. The main body portion can be formed from slightly lower index of refraction glass be clear glass or an ultraviolet absorbent Glass as it was mentioned earlier.

In the German Koester application A 46 719 VIIIo / 21g _f 55 of July 29, 1964 a laeerstructure is described "in which absorbent glass supports are used which are not necessarily saturable absorbers Glasses with bivalent Ε1β η,

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serve the nÖ. dive purpose, nod axial laser emission to absorb and thereby increase the permissible occupancy inversion of the Ij & serstructure »

One obtains «was the most effective operating arrangement of the laser structure» if dft «highly reflective, heat-conducting · Material in intimate contact with the side wall sections of the main body part 12, 12 * or 12 "stands for it is äedoea also sometimes possible, instead of this an environmental layer of such material, do use that is fixed to the Sidewall absehnitten of the main body part is arranged} even then you get even better results. Naturally the »wide layer 32 or 32 * can then be arranged around this first layer on request ·

as previously stated, the volume of the main body portion to a minimum compared to the dimension of the rod and the hole used, it follows that £ the cross-sectional area of the main body part glass as small as possible, relative to the cross-section of the surface of the ordered laser tab and dtr associated hole is held, and a ratio of as small a size as 5 «u 1 and even of 2 ία 1 is possible »'-. '- p,: r -

Patents

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Claims (1)

\ will ί dea 31 »Hfe * 1967 1. Laeeretstruktur (10) »it tiiaem ÄiiBZi * n tta main body part (12) «tte αϊ« «, w * leht» for di * opti energy «£ & e« let, uad (14) «ή« 0Im ₁ weloli * »eis · * laetra & ti-« atlillt, smooth tnw, tlaiüce uad Iaftt7iuu.li d ** H «uptlbody * rt« il »(12) so a "f" OTd "" t is ι d * ft "tlttt itltd" if * 3ad * b "iilixdtt · ait di «i ·» about dl · Χίβϋβ «4 # β lauptkiaff * rt # ile (12) ia optieofe« lontaltt »lad, wo ^ tl dlt Briohaag» l «d» ya des Gl «se« of the H * uytk5rp * rt «ili (It)« Hd d »e £ L * ae« of the laser coaponenso nüiasjftder f «tttg« ^ tft eiiid, that we have already done «La · öreaeflieii · (19) alt ^ orb * etl« Mter Diff treae de * Is-töiäua ^ are «··)» «» it * en _t daduroii st «k β aa *« ί #. It & tf am * la IHMptWrpert * !! (12) tia « wthex Iaobi> ftPMiuUrt «It der lit u »4 ·! ** 1 * r (1%) g Style & ** AÄÄg · i # s fi «eptk8ff? F **» iXe (Ii) «yet ^ eekt, dal : ' BATH- 009041/1450 Λ. gas served Sammer (18) afegeselilossen lit, with «in« * ionisierfcarem @as filled int, that »in (20, 22) durcfc. the main body (12) in the-Ifaesfcarsehaft tob which both lands (1 £ a _f 12b) is worn and its hole (16) extends * SaS «ä the end a of the Laetrkoaponeat; ® optlenh. f «in baw, fine ee» polished surfaces. Törgeiehen simd, mud d * fl a relmtir thin Söhiclit mm hociigrftdig refltkti «- 3? * Ndee thermally conductive» Materiftl (30) d »* H & uptlt5rper- & eil (12) over the larger price« tine? Lä £ «e üÄ grasps iind old feeteiti on its side # nw * nÄ * feseimiti;« ii (1 £ c) 2. Laser structure nfioii Anspruöii I ₉ dad'oröii. g β k # η be η η et _t d * JS the thin »Sahicht (30)« ui reflective "viral-guiding" material in intimate keatafet with the side edge abioniiits (12 ") of the main body part (12) is arranged. 5 · Laser structure aftch Asmpruoh 1 or g ₉ d ** arek g »· ident ^ eitnet» dat with noeagrmdif reflaktiaseaden coats (25 * 21), weXwÄe on vemigatem * a Α · τ fe * I * the mdfl & enen of the load component arranged » tad, £ & the later component is an integral part of the ti - 009841/1456 ~ 23 - Laier structure according to one of the requirements 1 to 3 g β ke η η it β ic has that the "total qu # reohnitti: iäohe dea Glaae" dee main body parts (12) in the weeentliclien * u a "minimum in comparison, with the cross-sectional areas of the tomMa * tion" us Boiiruiig ( 16) waä. Lmfierkoaponente (14) reduBi «rt iit» 5 * Laaeratriilctur nach one »dar speeches 1 feie 3, dmdurcii g β ke η a % eic h. η β t, that the total "transverse surface area of the Slaeea de · main body parts (12) is smaller than the combined transverse surface area ftii. 6 · liejieretröktar according to a · * der Anepriiohe 1 Me 5, dädmrök g β kea η * e 1 c k & et, that the main body part in the week borrowed in »Ilen« has a cross-section the size of a sllipie « 7, Laeeretstruktur after one of the test 1 to 6, thereby g * kensi t that a wide layer (52) of heat-conducting material allows to go, which has a greater thickness than the previous layer (30), including the AuSenfliehe he arranged whose LSnfe "th layer (JO) via the Gröb-th partial sound let Waa calibrated with the * jeer is in intimate contact. ■■; ■ ^: - 24- - 00984 1/1456 8. laser structure n & eh one »of claims 1 to 7» dftby g «kta & tel0liaet that the poneate au * «ines core (14 *) of the LaserglsLeea is, which contains a lass rfälilg en 2tes * ts, and that this kernel τοη a Slastmflaee (44) ximgebea is "which" tnan la * erliclit ".l5eortderendeÄ Susat" bare. L * «« r structure according to one of the Aosprlöhe 1 to 3, kenas ei paves, that eiae Wehrsahl (38) on the outer surface of the 'wide layer; (32) ta Kiifttslct; ait this atigGO.rdo.et is lind »icJii tob -this ScMoht meh ": oii * n & 1j @ Kiiisl" Lixr-iehtuj5 "der Laeer- 10 «Lcserstr ^ iM ^^ mmtM eiaes der Ansp2? Äeiie 1 Ms 9 t omAxüxsii gekeass el © -Ji a« t »4ai sie eime Waad (42)» mf shows a Mefcrsslil τοη Metalirippem 1 »sw · (JS) se i »gil» t ₉ d * fi »la * Eelirsalil toä fiiii- ea for al »during operation of the Iias structure vm lmufesi ·« coolant is formed « BATH 009841 / U56